Rubber General

What is Rubber?

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When people talk about “rubber”, they don’t usually specify what kind. There are many different kinds of rubber, but they all fall into two broad types: natural rubber (latex—grown from plants) and synthetic rubber (made artificially in a chemical plant or laboratory). Commercially, the most important synthetic rubbers are styrene butadiene (SBR), polyacrylics, and polyvinyl acetate (PVA); other kinds include polyvinyl chloride (PVC), polychloroprene (better known as neoprene), and various types of polyurethane. Although natural rubber and synthetic rubbers are similar in some ways, they’re made by entirely different processes and chemically quite different.

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How rubber is made?

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Natural rubber is made from a runny, milky white liquid called latex that oozes from certain plants when you cut into them. (Common dandelions, for example, produce latex; if you snap off their stems, you can see the latex dripping out from them. In theory, there’s no reason why we couldn’t make rubber by growing dandelions, though we’d need an awful lot of them.) Although there are something like 200 plants in the world that produce latex, over 99 percent of the world’s natural rubber is made from the latex that comes from a tree species called Hevea brasiliensis, widely known as the rubber tree. This latex is about one third water and one third rubber particles held in a form known as a colloidal suspension. Natural rubber is a polymer of isoprene (also known as 2-methylbuta-1,3-diene) with the chemical formula (C5H8)n. To put it more simply, it’s made of many thousands of basic C5H8 units (the monomer of isoprene) loosely joined to make long, tangled chains. These chains of molecules can be pulled apart and untangled fairly easily, but they spring straight back together if you release them—and that’s what makes rubber elastic.